1. Field of the Invention
This invention relates to the field of devices for coordinating the closing sequence of a pair of double doors having a common line of closure. More particularly it relates to door coordinators which have a trigger and a stop, the stop holding the active door open until the inactive door forces the trigger to retract and then the stop to retract permitting the active door to close.
2. Description of Related Art
Door coordinators of the prior art are discussed generally in, for example, U.S. Pat. No. 3,822,506 (the '506 patent) and U.S. Pat. No. 3,895,461 (the '461 patent). Door coordinators generally are mounted on the top underside of a door frame and have a trigger member and a stop member. The stop member blocks the "active" door from closing until the "inactive" door has finished closing and has triggered the trigger member. In the '506 patent, for example, the stop member 34 may (upon application of force to the stop member) rotate about pivot point 36 once trigger 40 is depressed. In the '461 patent stop member 28 may (upon application of force to the stop member) rotate about pivot point 36 upon activation of pivoting trigger 48. A feature incorporated in most door coordinators is the "override." The override is designed to prevent damage to the door, door hinges, door frame and coordinator in the event someone pushes on the active door in an attempt to close it prior to the closing of the inactive door (and triggering of the door coordinator). The stop member of a door coordinator is generally located as close to the hinges of the active door as possible. This minimizes the protrusion of the stop member necessary in order to hold the active door sufficiently open to permit the inactive door to swing by the active door and close. Consequently, a great deal of leverage can be exercised upon the wedge presented by the stop member by one intent upon closing the doors out of sequence. Although fit for their intended purposes, door coordinators of the prior art have experienced problems of excess wear, rough operation and erratic override force especially with operation of the override feature. Such erratic override force may result in broken door hinges and inoperative doors due to excessive resistance to override on the part of the door coordinator. Many prior art door coordinators employ cams and sliding surfaces (see, e.g., FIG. 3 of the '506 patent and FIGS. 1 and 2 of the '461 patent). The friction of the cams and sliding surfaces can vary with wear, lubrication and surface finish resulting in unpredictable and changing amounts of force being required to engage the oVerride feature. As a consequence, a need exists for an improved door coordinator having improved smoothness of operation, improved adjustability of the override threshold, less friction in operation and an improved override feature.